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simplesshd/openssh/sftp-server.c

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/* $OpenBSD: sftp-server.c,v 1.103 2014/01/17 06:23:24 dtucker Exp $ */
/*
* Copyright (c) 2000-2004 Markus Friedl. All rights reserved.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#include <sys/types.h>
#include <sys/param.h>
#include <sys/stat.h>
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#ifdef HAVE_SYS_MOUNT_H
#include <sys/mount.h>
#endif
#ifdef HAVE_SYS_PRCTL_H
#include <sys/prctl.h>
#endif
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <stdarg.h>
#include "xmalloc.h"
#include "buffer.h"
#include "misc.h"
#include "match.h"
#include "sftp.h"
#include "sftp-common.h"
/* helper */
#define get_int64() buffer_get_int64(&iqueue);
#define get_int() buffer_get_int(&iqueue);
#define get_string(lenp) buffer_get_string(&iqueue, lenp);
/* Our client */
static char *client_addr = NULL;
/* input and output queue */
static Buffer iqueue;
static Buffer oqueue;
/* Version of client */
static u_int version;
/* SSH2_FXP_INIT received */
static int init_done;
/* Disable writes */
static int readonly;
/* Requests that are allowed/denied */
static char *request_whitelist, *request_blacklist;
/* portable attributes, etc. */
typedef struct Stat Stat;
struct Stat {
char *name;
char *long_name;
Attrib attrib;
};
/* Packet handlers */
static void process_open(u_int32_t id);
static void process_close(u_int32_t id);
static void process_read(u_int32_t id);
static void process_write(u_int32_t id);
static void process_stat(u_int32_t id);
static void process_lstat(u_int32_t id);
static void process_fstat(u_int32_t id);
static void process_setstat(u_int32_t id);
static void process_fsetstat(u_int32_t id);
static void process_opendir(u_int32_t id);
static void process_readdir(u_int32_t id);
static void process_remove(u_int32_t id);
static void process_mkdir(u_int32_t id);
static void process_rmdir(u_int32_t id);
static void process_realpath(u_int32_t id);
static void process_rename(u_int32_t id);
static void process_readlink(u_int32_t id);
static void process_symlink(u_int32_t id);
static void process_extended_posix_rename(u_int32_t id);
static void process_extended_hardlink(u_int32_t id);
static void process_extended_fsync(u_int32_t id);
static void process_extended(u_int32_t id);
struct sftp_handler {
const char *name; /* user-visible name for fine-grained perms */
const char *ext_name; /* extended request name */
u_int type; /* packet type, for non extended packets */
void (*handler)(u_int32_t);
int does_write; /* if nonzero, banned for readonly mode */
};
struct sftp_handler handlers[] = {
/* NB. SSH2_FXP_OPEN does the readonly check in the handler itself */
{ "open", NULL, SSH2_FXP_OPEN, process_open, 0 },
{ "close", NULL, SSH2_FXP_CLOSE, process_close, 0 },
{ "read", NULL, SSH2_FXP_READ, process_read, 0 },
{ "write", NULL, SSH2_FXP_WRITE, process_write, 1 },
{ "lstat", NULL, SSH2_FXP_LSTAT, process_lstat, 0 },
{ "fstat", NULL, SSH2_FXP_FSTAT, process_fstat, 0 },
{ "setstat", NULL, SSH2_FXP_SETSTAT, process_setstat, 1 },
{ "fsetstat", NULL, SSH2_FXP_FSETSTAT, process_fsetstat, 1 },
{ "opendir", NULL, SSH2_FXP_OPENDIR, process_opendir, 0 },
{ "readdir", NULL, SSH2_FXP_READDIR, process_readdir, 0 },
{ "remove", NULL, SSH2_FXP_REMOVE, process_remove, 1 },
{ "mkdir", NULL, SSH2_FXP_MKDIR, process_mkdir, 1 },
{ "rmdir", NULL, SSH2_FXP_RMDIR, process_rmdir, 1 },
{ "realpath", NULL, SSH2_FXP_REALPATH, process_realpath, 0 },
{ "stat", NULL, SSH2_FXP_STAT, process_stat, 0 },
{ "rename", NULL, SSH2_FXP_RENAME, process_rename, 1 },
{ "readlink", NULL, SSH2_FXP_READLINK, process_readlink, 0 },
{ "symlink", NULL, SSH2_FXP_SYMLINK, process_symlink, 1 },
{ NULL, NULL, 0, NULL, 0 }
};
/* SSH2_FXP_EXTENDED submessages */
struct sftp_handler extended_handlers[] = {
{ "posix-rename", "posix-rename@openssh.com", 0,
process_extended_posix_rename, 1 },
{ "hardlink", "hardlink@openssh.com", 0, process_extended_hardlink, 1 },
{ "fsync", "fsync@openssh.com", 0, process_extended_fsync, 1 },
{ NULL, NULL, 0, NULL, 0 }
};
static int
request_permitted(struct sftp_handler *h)
{
char *result;
if (readonly && h->does_write) {
return 0;
}
if (request_blacklist != NULL &&
((result = match_list(h->name, request_blacklist, NULL))) != NULL) {
free(result);
return 0;
}
if (request_whitelist != NULL &&
((result = match_list(h->name, request_whitelist, NULL))) != NULL) {
free(result);
return 1;
}
if (request_whitelist != NULL) {
return 0;
}
return 1;
}
static int
errno_to_portable(int unixerrno)
{
int ret = 0;
switch (unixerrno) {
case 0:
ret = SSH2_FX_OK;
break;
case ENOENT:
case ENOTDIR:
case EBADF:
case ELOOP:
ret = SSH2_FX_NO_SUCH_FILE;
break;
case EPERM:
case EACCES:
case EFAULT:
ret = SSH2_FX_PERMISSION_DENIED;
break;
case ENAMETOOLONG:
case EINVAL:
ret = SSH2_FX_BAD_MESSAGE;
break;
case ENOSYS:
ret = SSH2_FX_OP_UNSUPPORTED;
break;
default:
ret = SSH2_FX_FAILURE;
break;
}
return ret;
}
static int
flags_from_portable(int pflags)
{
int flags = 0;
if ((pflags & SSH2_FXF_READ) &&
(pflags & SSH2_FXF_WRITE)) {
flags = O_RDWR;
} else if (pflags & SSH2_FXF_READ) {
flags = O_RDONLY;
} else if (pflags & SSH2_FXF_WRITE) {
flags = O_WRONLY;
}
if (pflags & SSH2_FXF_APPEND)
flags |= O_APPEND;
if (pflags & SSH2_FXF_CREAT)
flags |= O_CREAT;
if (pflags & SSH2_FXF_TRUNC)
flags |= O_TRUNC;
if (pflags & SSH2_FXF_EXCL)
flags |= O_EXCL;
return flags;
}
static const char *
string_from_portable(int pflags)
{
static char ret[128];
*ret = '\0';
#define PAPPEND(str) { \
if (*ret != '\0') \
strlcat(ret, ",", sizeof(ret)); \
strlcat(ret, str, sizeof(ret)); \
}
if (pflags & SSH2_FXF_READ)
PAPPEND("READ")
if (pflags & SSH2_FXF_WRITE)
PAPPEND("WRITE")
if (pflags & SSH2_FXF_APPEND)
PAPPEND("APPEND")
if (pflags & SSH2_FXF_CREAT)
PAPPEND("CREATE")
if (pflags & SSH2_FXF_TRUNC)
PAPPEND("TRUNCATE")
if (pflags & SSH2_FXF_EXCL)
PAPPEND("EXCL")
return ret;
}
static Attrib *
get_attrib(void)
{
return decode_attrib(&iqueue);
}
/* handle handles */
typedef struct Handle Handle;
struct Handle {
int use;
DIR *dirp;
int fd;
int flags;
char *name;
u_int64_t bytes_read, bytes_write;
int next_unused;
};
enum {
HANDLE_UNUSED,
HANDLE_DIR,
HANDLE_FILE
};
Handle *handles = NULL;
u_int num_handles = 0;
int first_unused_handle = -1;
static void handle_unused(int i)
{
handles[i].use = HANDLE_UNUSED;
handles[i].next_unused = first_unused_handle;
first_unused_handle = i;
}
static int
handle_new(int use, const char *name, int fd, int flags, DIR *dirp)
{
int i;
if (first_unused_handle == -1) {
if (num_handles + 1 <= num_handles)
return -1;
num_handles++;
handles = xrealloc(handles, num_handles, sizeof(Handle));
handle_unused(num_handles - 1);
}
i = first_unused_handle;
first_unused_handle = handles[i].next_unused;
handles[i].use = use;
handles[i].dirp = dirp;
handles[i].fd = fd;
handles[i].flags = flags;
handles[i].name = xstrdup(name);
handles[i].bytes_read = handles[i].bytes_write = 0;
return i;
}
static int
handle_is_ok(int i, int type)
{
return i >= 0 && (u_int)i < num_handles && handles[i].use == type;
}
static int
handle_to_string(int handle, char **stringp, int *hlenp)
{
if (stringp == NULL || hlenp == NULL)
return -1;
*stringp = xmalloc(sizeof(int32_t));
put_u32(*stringp, handle);
*hlenp = sizeof(int32_t);
return 0;
}
static int
handle_from_string(const char *handle, u_int hlen)
{
int val;
if (hlen != sizeof(int32_t))
return -1;
val = get_u32(handle);
if (handle_is_ok(val, HANDLE_FILE) ||
handle_is_ok(val, HANDLE_DIR))
return val;
return -1;
}
static char *
handle_to_name(int handle)
{
if (handle_is_ok(handle, HANDLE_DIR)||
handle_is_ok(handle, HANDLE_FILE))
return handles[handle].name;
return NULL;
}
static DIR *
handle_to_dir(int handle)
{
if (handle_is_ok(handle, HANDLE_DIR))
return handles[handle].dirp;
return NULL;
}
static int
handle_to_fd(int handle)
{
if (handle_is_ok(handle, HANDLE_FILE))
return handles[handle].fd;
return -1;
}
static int
handle_to_flags(int handle)
{
if (handle_is_ok(handle, HANDLE_FILE))
return handles[handle].flags;
return 0;
}
static void
handle_update_read(int handle, ssize_t bytes)
{
if (handle_is_ok(handle, HANDLE_FILE) && bytes > 0)
handles[handle].bytes_read += bytes;
}
static void
handle_update_write(int handle, ssize_t bytes)
{
if (handle_is_ok(handle, HANDLE_FILE) && bytes > 0)
handles[handle].bytes_write += bytes;
}
static u_int64_t
handle_bytes_read(int handle)
{
if (handle_is_ok(handle, HANDLE_FILE))
return (handles[handle].bytes_read);
return 0;
}
static u_int64_t
handle_bytes_write(int handle)
{
if (handle_is_ok(handle, HANDLE_FILE))
return (handles[handle].bytes_write);
return 0;
}
static int
handle_close(int handle)
{
int ret = -1;
if (handle_is_ok(handle, HANDLE_FILE)) {
ret = close(handles[handle].fd);
free(handles[handle].name);
handle_unused(handle);
} else if (handle_is_ok(handle, HANDLE_DIR)) {
ret = closedir(handles[handle].dirp);
free(handles[handle].name);
handle_unused(handle);
} else {
errno = ENOENT;
}
return ret;
}
static int
get_handle(void)
{
char *handle;
int val = -1;
u_int hlen;
handle = get_string(&hlen);
if (hlen < 256)
val = handle_from_string(handle, hlen);
free(handle);
return val;
}
/* send replies */
static void
send_msg(Buffer *m)
{
int mlen = buffer_len(m);
buffer_put_int(&oqueue, mlen);
buffer_append(&oqueue, buffer_ptr(m), mlen);
buffer_consume(m, mlen);
}
static const char *
status_to_message(u_int32_t status)
{
const char *status_messages[] = {
"Success", /* SSH_FX_OK */
"End of file", /* SSH_FX_EOF */
"No such file", /* SSH_FX_NO_SUCH_FILE */
"Permission denied", /* SSH_FX_PERMISSION_DENIED */
"Failure", /* SSH_FX_FAILURE */
"Bad message", /* SSH_FX_BAD_MESSAGE */
"No connection", /* SSH_FX_NO_CONNECTION */
"Connection lost", /* SSH_FX_CONNECTION_LOST */
"Operation unsupported", /* SSH_FX_OP_UNSUPPORTED */
"Unknown error" /* Others */
};
return (status_messages[MIN(status,SSH2_FX_MAX)]);
}
static void
send_status(u_int32_t id, u_int32_t status)
{
Buffer msg;
buffer_init(&msg);
buffer_put_char(&msg, SSH2_FXP_STATUS);
buffer_put_int(&msg, id);
buffer_put_int(&msg, status);
if (version >= 3) {
buffer_put_cstring(&msg, status_to_message(status));
buffer_put_cstring(&msg, "");
}
send_msg(&msg);
buffer_free(&msg);
}
static void
send_data_or_handle(char type, u_int32_t id, const char *data, int dlen)
{
Buffer msg;
buffer_init(&msg);
buffer_put_char(&msg, type);
buffer_put_int(&msg, id);
buffer_put_string(&msg, data, dlen);
send_msg(&msg);
buffer_free(&msg);
}
static void
send_data(u_int32_t id, const char *data, int dlen)
{
send_data_or_handle(SSH2_FXP_DATA, id, data, dlen);
}
static void
send_handle(u_int32_t id, int handle)
{
char *string;
int hlen;
handle_to_string(handle, &string, &hlen);
send_data_or_handle(SSH2_FXP_HANDLE, id, string, hlen);
free(string);
}
static void
send_names(u_int32_t id, int count, const Stat *stats)
{
Buffer msg;
int i;
buffer_init(&msg);
buffer_put_char(&msg, SSH2_FXP_NAME);
buffer_put_int(&msg, id);
buffer_put_int(&msg, count);
for (i = 0; i < count; i++) {
buffer_put_cstring(&msg, stats[i].name);
buffer_put_cstring(&msg, stats[i].long_name);
encode_attrib(&msg, &stats[i].attrib);
}
send_msg(&msg);
buffer_free(&msg);
}
static void
send_attrib(u_int32_t id, const Attrib *a)
{
Buffer msg;
buffer_init(&msg);
buffer_put_char(&msg, SSH2_FXP_ATTRS);
buffer_put_int(&msg, id);
encode_attrib(&msg, a);
send_msg(&msg);
buffer_free(&msg);
}
/* parse incoming */
static void
process_init(void)
{
Buffer msg;
version = get_int();
buffer_init(&msg);
buffer_put_char(&msg, SSH2_FXP_VERSION);
buffer_put_int(&msg, SSH2_FILEXFER_VERSION);
/* POSIX rename extension */
buffer_put_cstring(&msg, "posix-rename@openssh.com");
buffer_put_cstring(&msg, "1"); /* version */
/* hardlink extension */
buffer_put_cstring(&msg, "hardlink@openssh.com");
buffer_put_cstring(&msg, "1"); /* version */
/* fsync extension */
buffer_put_cstring(&msg, "fsync@openssh.com");
buffer_put_cstring(&msg, "1"); /* version */
send_msg(&msg);
buffer_free(&msg);
}
static void
process_open(u_int32_t id)
{
u_int32_t pflags;
Attrib *a;
char *name;
int handle, fd, flags, mode, status = SSH2_FX_FAILURE;
name = get_string(NULL);
pflags = get_int(); /* portable flags */
a = get_attrib();
flags = flags_from_portable(pflags);
mode = (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) ? a->perm : 0666;
if (readonly &&
((flags & O_ACCMODE) == O_WRONLY ||
(flags & O_ACCMODE) == O_RDWR)) {
status = SSH2_FX_PERMISSION_DENIED;
} else {
fd = open(name, flags, mode);
if (fd < 0) {
status = errno_to_portable(errno);
} else {
handle = handle_new(HANDLE_FILE, name, fd, flags, NULL);
if (handle < 0) {
close(fd);
} else {
send_handle(id, handle);
status = SSH2_FX_OK;
}
}
}
if (status != SSH2_FX_OK)
send_status(id, status);
free(name);
}
static void
process_close(u_int32_t id)
{
int handle, ret, status = SSH2_FX_FAILURE;
handle = get_handle();
ret = handle_close(handle);
status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
send_status(id, status);
}
static void
process_read(u_int32_t id)
{
char buf[64*1024];
u_int32_t len;
int handle, fd, ret, status = SSH2_FX_FAILURE;
u_int64_t off;
handle = get_handle();
off = get_int64();
len = get_int();
if (len > sizeof buf) {
len = sizeof buf;
}
fd = handle_to_fd(handle);
if (fd >= 0) {
if (lseek(fd, off, SEEK_SET) < 0) {
error("process_read: seek failed");
status = errno_to_portable(errno);
} else {
ret = read(fd, buf, len);
if (ret < 0) {
status = errno_to_portable(errno);
} else if (ret == 0) {
status = SSH2_FX_EOF;
} else {
send_data(id, buf, ret);
status = SSH2_FX_OK;
handle_update_read(handle, ret);
}
}
}
if (status != SSH2_FX_OK)
send_status(id, status);
}
static void
process_write(u_int32_t id)
{
u_int64_t off;
u_int len;
int handle, fd, ret, status;
char *data;
handle = get_handle();
off = get_int64();
data = get_string(&len);
fd = handle_to_fd(handle);
if (fd < 0)
status = SSH2_FX_FAILURE;
else {
if (!(handle_to_flags(handle) & O_APPEND) &&
lseek(fd, off, SEEK_SET) < 0) {
status = errno_to_portable(errno);
error("process_write: seek failed");
} else {
/* XXX ATOMICIO ? */
ret = write(fd, data, len);
if (ret < 0) {
error("process_write: write failed");
status = errno_to_portable(errno);
} else if ((size_t)ret == len) {
status = SSH2_FX_OK;
handle_update_write(handle, ret);
} else {
status = SSH2_FX_FAILURE;
}
}
}
send_status(id, status);
free(data);
}
static void
process_do_stat(u_int32_t id, int do_lstat)
{
Attrib a;
struct stat st;
char *name;
int ret, status = SSH2_FX_FAILURE;
name = get_string(NULL);
ret = do_lstat ? lstat(name, &st) : stat(name, &st);
if (ret < 0) {
status = errno_to_portable(errno);
} else {
stat_to_attrib(&st, &a);
send_attrib(id, &a);
status = SSH2_FX_OK;
}
if (status != SSH2_FX_OK)
send_status(id, status);
free(name);
}
static void
process_stat(u_int32_t id)
{
process_do_stat(id, 0);
}
static void
process_lstat(u_int32_t id)
{
process_do_stat(id, 1);
}
static void
process_fstat(u_int32_t id)
{
Attrib a;
struct stat st;
int fd, ret, handle, status = SSH2_FX_FAILURE;
handle = get_handle();
fd = handle_to_fd(handle);
if (fd >= 0) {
ret = fstat(fd, &st);
if (ret < 0) {
status = errno_to_portable(errno);
} else {
stat_to_attrib(&st, &a);
send_attrib(id, &a);
status = SSH2_FX_OK;
}
}
if (status != SSH2_FX_OK)
send_status(id, status);
}
static struct timeval *
attrib_to_tv(const Attrib *a)
{
static struct timeval tv[2];
tv[0].tv_sec = a->atime;
tv[0].tv_usec = 0;
tv[1].tv_sec = a->mtime;
tv[1].tv_usec = 0;
return tv;
}
static void
process_setstat(u_int32_t id)
{
Attrib *a;
char *name;
int status = SSH2_FX_OK, ret;
name = get_string(NULL);
a = get_attrib();
if (a->flags & SSH2_FILEXFER_ATTR_SIZE) {
ret = truncate(name, a->size);
if (ret == -1)
status = errno_to_portable(errno);
}
if (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) {
ret = chmod(name, a->perm & 07777);
if (ret == -1)
status = errno_to_portable(errno);
}
if (a->flags & SSH2_FILEXFER_ATTR_ACMODTIME) {
char buf[64];
time_t t = a->mtime;
strftime(buf, sizeof(buf), "%Y%m%d-%H:%M:%S",
localtime(&t));
ret = utimes(name, attrib_to_tv(a));
if (ret == -1)
status = errno_to_portable(errno);
}
if (a->flags & SSH2_FILEXFER_ATTR_UIDGID) {
ret = chown(name, a->uid, a->gid);
if (ret == -1)
status = errno_to_portable(errno);
}
send_status(id, status);
free(name);
}
static void
process_fsetstat(u_int32_t id)
{
Attrib *a;
int handle, fd, ret;
int status = SSH2_FX_OK;
handle = get_handle();
a = get_attrib();
fd = handle_to_fd(handle);
if (fd < 0)
status = SSH2_FX_FAILURE;
else {
char *name = handle_to_name(handle);
if (a->flags & SSH2_FILEXFER_ATTR_SIZE) {
ret = ftruncate(fd, a->size);
if (ret == -1)
status = errno_to_portable(errno);
}
if (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) {
#ifdef HAVE_FCHMOD
ret = fchmod(fd, a->perm & 07777);
#else
ret = chmod(name, a->perm & 07777);
#endif
if (ret == -1)
status = errno_to_portable(errno);
}
if (a->flags & SSH2_FILEXFER_ATTR_ACMODTIME) {
#ifdef HAVE_FUTIMES
ret = futimes(fd, attrib_to_tv(a));
#else
ret = utimes(name, attrib_to_tv(a));
#endif
if (ret == -1)
status = errno_to_portable(errno);
}
if (a->flags & SSH2_FILEXFER_ATTR_UIDGID) {
#ifdef HAVE_FCHOWN
ret = fchown(fd, a->uid, a->gid);
#else
ret = chown(name, a->uid, a->gid);
#endif
if (ret == -1)
status = errno_to_portable(errno);
}
}
send_status(id, status);
}
static void
process_opendir(u_int32_t id)
{
DIR *dirp = NULL;
char *path;
int handle, status = SSH2_FX_FAILURE;
path = get_string(NULL);
dirp = opendir(path);
if (dirp == NULL) {
status = errno_to_portable(errno);
} else {
handle = handle_new(HANDLE_DIR, path, 0, 0, dirp);
if (handle < 0) {
closedir(dirp);
} else {
send_handle(id, handle);
status = SSH2_FX_OK;
}
}
if (status != SSH2_FX_OK)
send_status(id, status);
free(path);
}
static void
process_readdir(u_int32_t id)
{
DIR *dirp;
struct dirent *dp;
char *path;
int handle;
handle = get_handle();
dirp = handle_to_dir(handle);
path = handle_to_name(handle);
if (dirp == NULL || path == NULL) {
send_status(id, SSH2_FX_FAILURE);
} else {
struct stat st;
char pathname[MAXPATHLEN];
Stat *stats;
int nstats = 10, count = 0, i;
stats = xcalloc(nstats, sizeof(Stat));
while ((dp = readdir(dirp)) != NULL) {
if (count >= nstats) {
nstats *= 2;
stats = xrealloc(stats, nstats, sizeof(Stat));
}
/* XXX OVERFLOW ? */
snprintf(pathname, sizeof pathname, "%s%s%s", path,
strcmp(path, "/") ? "/" : "", dp->d_name);
if (lstat(pathname, &st) < 0)
continue;
stat_to_attrib(&st, &(stats[count].attrib));
stats[count].name = xstrdup(dp->d_name);
stats[count].long_name = ls_file(dp->d_name, &st, 0, 0);
count++;
/* send up to 100 entries in one message */
/* XXX check packet size instead */
if (count == 100)
break;
}
if (count > 0) {
send_names(id, count, stats);
for (i = 0; i < count; i++) {
free(stats[i].name);
free(stats[i].long_name);
}
} else {
send_status(id, SSH2_FX_EOF);
}
free(stats);
}
}
static void
process_remove(u_int32_t id)
{
char *name;
int status = SSH2_FX_FAILURE;
int ret;
name = get_string(NULL);
ret = unlink(name);
status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
send_status(id, status);
free(name);
}
static void
process_mkdir(u_int32_t id)
{
Attrib *a;
char *name;
int ret, mode, status = SSH2_FX_FAILURE;
name = get_string(NULL);
a = get_attrib();
mode = (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) ?
a->perm & 07777 : 0777;
ret = mkdir(name, mode);
status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
send_status(id, status);
free(name);
}
static void
process_rmdir(u_int32_t id)
{
char *name;
int ret, status;
name = get_string(NULL);
ret = rmdir(name);
status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
send_status(id, status);
free(name);
}
static void
process_realpath(u_int32_t id)
{
char resolvedname[MAXPATHLEN];
char *path;
path = get_string(NULL);
if (path[0] == '\0') {
free(path);
path = xstrdup(".");
}
if (realpath(path, resolvedname) == NULL) {
send_status(id, errno_to_portable(errno));
} else {
Stat s;
attrib_clear(&s.attrib);
s.name = s.long_name = resolvedname;
send_names(id, 1, &s);
}
free(path);
}
static void
process_rename(u_int32_t id)
{
char *oldpath, *newpath;
int status;
struct stat sb;
oldpath = get_string(NULL);
newpath = get_string(NULL);
status = SSH2_FX_FAILURE;
if (lstat(oldpath, &sb) == -1)
status = errno_to_portable(errno);
else if (S_ISREG(sb.st_mode)) {
/* Race-free rename of regular files */
if (link(oldpath, newpath) == -1) {
if (errno == EOPNOTSUPP || errno == ENOSYS
#ifdef EXDEV
|| errno == EXDEV
#endif
#ifdef LINK_OPNOTSUPP_ERRNO
|| errno == LINK_OPNOTSUPP_ERRNO
#endif
) {
struct stat st;
/*
* fs doesn't support links, so fall back to
* stat+rename. This is racy.
*/
if (stat(newpath, &st) == -1) {
if (rename(oldpath, newpath) == -1)
status =
errno_to_portable(errno);
else
status = SSH2_FX_OK;
}
} else {
status = errno_to_portable(errno);
}
} else if (unlink(oldpath) == -1) {
status = errno_to_portable(errno);
/* clean spare link */
unlink(newpath);
} else
status = SSH2_FX_OK;
} else if (stat(newpath, &sb) == -1) {
if (rename(oldpath, newpath) == -1)
status = errno_to_portable(errno);
else
status = SSH2_FX_OK;
}
send_status(id, status);
free(oldpath);
free(newpath);
}
static void
process_readlink(u_int32_t id)
{
int len;
char buf[MAXPATHLEN];
char *path;
path = get_string(NULL);
if ((len = readlink(path, buf, sizeof(buf) - 1)) == -1)
send_status(id, errno_to_portable(errno));
else {
Stat s;
buf[len] = '\0';
attrib_clear(&s.attrib);
s.name = s.long_name = buf;
send_names(id, 1, &s);
}
free(path);
}
static void
process_symlink(u_int32_t id)
{
char *oldpath, *newpath;
int ret, status;
oldpath = get_string(NULL);
newpath = get_string(NULL);
/* this will fail if 'newpath' exists */
ret = symlink(oldpath, newpath);
status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
send_status(id, status);
free(oldpath);
free(newpath);
}
static void
process_extended_posix_rename(u_int32_t id)
{
char *oldpath, *newpath;
int ret, status;
oldpath = get_string(NULL);
newpath = get_string(NULL);
ret = rename(oldpath, newpath);
status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
send_status(id, status);
free(oldpath);
free(newpath);
}
static void
process_extended_hardlink(u_int32_t id)
{
char *oldpath, *newpath;
int ret, status;
oldpath = get_string(NULL);
newpath = get_string(NULL);
ret = link(oldpath, newpath);
status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
send_status(id, status);
free(oldpath);
free(newpath);
}
static void
process_extended_fsync(u_int32_t id)
{
int handle, fd, ret, status = SSH2_FX_OP_UNSUPPORTED;
handle = get_handle();
if ((fd = handle_to_fd(handle)) < 0)
status = SSH2_FX_NO_SUCH_FILE;
else if (handle_is_ok(handle, HANDLE_FILE)) {
ret = fsync(fd);
status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
}
send_status(id, status);
}
static void
process_extended(u_int32_t id)
{
char *request;
u_int i;
request = get_string(NULL);
for (i = 0; extended_handlers[i].handler != NULL; i++) {
if (strcmp(request, extended_handlers[i].ext_name) == 0) {
if (!request_permitted(&extended_handlers[i]))
send_status(id, SSH2_FX_PERMISSION_DENIED);
else
extended_handlers[i].handler(id);
break;
}
}
if (extended_handlers[i].handler == NULL) {
error("Unknown extended request \"%.100s\"", request);
send_status(id, SSH2_FX_OP_UNSUPPORTED); /* MUST */
}
free(request);
}
/* stolen from ssh-agent */
static void
process(void)
{
u_int msg_len, buf_len, consumed, type, i;
u_char *cp;
u_int32_t id;
buf_len = buffer_len(&iqueue);
if (buf_len < 5)
return; /* Incomplete message. */
cp = buffer_ptr(&iqueue);
msg_len = get_u32(cp);
if (msg_len > SFTP_MAX_MSG_LENGTH) {
error("bad message from %s", client_addr);
sftp_server_cleanup_exit(11);
}
if (buf_len < msg_len + 4)
return;
buffer_consume(&iqueue, 4);
buf_len -= 4;
type = buffer_get_char(&iqueue);
switch (type) {
case SSH2_FXP_INIT:
process_init();
init_done = 1;
break;
case SSH2_FXP_EXTENDED:
if (!init_done)
fatal("Received extended request before init");
id = get_int();
process_extended(id);
break;
default:
if (!init_done)
fatal("Received %u request before init", type);
id = get_int();
for (i = 0; handlers[i].handler != NULL; i++) {
if (type == handlers[i].type) {
if (!request_permitted(&handlers[i])) {
send_status(id,
SSH2_FX_PERMISSION_DENIED);
} else {
handlers[i].handler(id);
}
break;
}
}
if (handlers[i].handler == NULL)
error("Unknown message %u", type);
}
/* discard the remaining bytes from the current packet */
if (buf_len < buffer_len(&iqueue)) {
error("iqueue grew unexpectedly");
sftp_server_cleanup_exit(255);
}
consumed = buf_len - buffer_len(&iqueue);
if (msg_len < consumed) {
error("msg_len %u < consumed %u", msg_len, consumed);
sftp_server_cleanup_exit(255);
}
if (msg_len > consumed)
buffer_consume(&iqueue, msg_len - consumed);
}
/* Cleanup handler that logs active handles upon normal exit */
void
sftp_server_cleanup_exit(int i)
{
_exit(i);
}
int
sftp_server_main(int argc, char **argv)
{
fd_set rsetx, wsetx;
fd_set *rset = &rsetx, *wset = &wsetx;
int i, in, out, max, ch, skipargs = 0;
ssize_t len, olen;
char *cp, *homedir = NULL, buf[4*4096];
long mask;
extern char *optarg;
while (!skipargs && (ch = getopt(argc, argv,
"d:f:l:P:p:Q:u:cehR")) != -1) {
switch (ch) {
case 'Q':
if (strcasecmp(optarg, "requests") != 0) {
fprintf(stderr, "Invalid query type\n");
exit(1);
}
for (i = 0; handlers[i].handler != NULL; i++)
printf("%s\n", handlers[i].name);
for (i = 0; extended_handlers[i].handler != NULL; i++)
printf("%s\n", extended_handlers[i].name);
exit(0);
break;
case 'R':
readonly = 1;
break;
case 'c':
/*
* Ignore all arguments if we are invoked as a
* shell using "sftp-server -c command"
*/
skipargs = 1;
break;
case 'p':
if (request_whitelist != NULL)
fatal("Permitted requests already set");
request_whitelist = xstrdup(optarg);
break;
case 'P':
if (request_blacklist != NULL)
fatal("Refused requests already set");
request_blacklist = xstrdup(optarg);
break;
case 'u':
errno = 0;
mask = strtol(optarg, &cp, 8);
if (mask < 0 || mask > 0777 || *cp != '\0' ||
cp == optarg || (mask == 0 && errno != 0))
fatal("Invalid umask \"%s\"", optarg);
(void)umask((mode_t)mask);
break;
}
}
#if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
/*
* On Linux, we should try to avoid making /proc/self/{mem,maps}
* available to the user so that sftp access doesn't automatically
* imply arbitrary code execution access that will break
* restricted configurations.
*/
if (prctl(PR_SET_DUMPABLE, 0) != 0)
fatal("unable to make the process undumpable");
#endif /* defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE) */
if ((cp = getenv("SSH_CONNECTION")) != NULL) {
client_addr = xstrdup(cp);
if ((cp = strchr(client_addr, ' ')) == NULL) {
error("Malformed SSH_CONNECTION variable: \"%s\"",
getenv("SSH_CONNECTION"));
sftp_server_cleanup_exit(255);
}
*cp = '\0';
} else
client_addr = xstrdup("UNKNOWN");
in = STDIN_FILENO;
out = STDOUT_FILENO;
#ifdef HAVE_CYGWIN
setmode(in, O_BINARY);
setmode(out, O_BINARY);
#endif
max = 0;
if (in > max)
max = in;
if (out > max)
max = out;
buffer_init(&iqueue);
buffer_init(&oqueue);
if (homedir != NULL) {
if (chdir(homedir) != 0) {
error("chdir to \"%s\" failed: %s", homedir,
strerror(errno));
}
}
for (;;) {
FD_ZERO(rset);
FD_ZERO(wset);
/*
* Ensure that we can read a full buffer and handle
* the worst-case length packet it can generate,
* otherwise apply backpressure by stopping reads.
*/
if (buffer_check_alloc(&iqueue, sizeof(buf)) &&
buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
FD_SET(in, rset);
olen = buffer_len(&oqueue);
if (olen > 0)
FD_SET(out, wset);
if (select(max+1, rset, wset, NULL, NULL) < 0) {
if (errno == EINTR)
continue;
error("select: %s", strerror(errno));
sftp_server_cleanup_exit(2);
}
/* copy stdin to iqueue */
if (FD_ISSET(in, rset)) {
len = read(in, buf, sizeof buf);
if (len == 0) {
sftp_server_cleanup_exit(0);
} else if (len < 0) {
error("read: %s", strerror(errno));
sftp_server_cleanup_exit(1);
} else {
buffer_append(&iqueue, buf, len);
}
}
/* send oqueue to stdout */
if (FD_ISSET(out, wset)) {
len = write(out, buffer_ptr(&oqueue), olen);
if (len < 0) {
error("write: %s", strerror(errno));
sftp_server_cleanup_exit(1);
} else {
buffer_consume(&oqueue, len);
}
}
/*
* Process requests from client if we can fit the results
* into the output buffer, otherwise stop processing input
* and let the output queue drain.
*/
if (buffer_check_alloc(&oqueue, SFTP_MAX_MSG_LENGTH))
process();
}
}
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